Fitted mattress pads and sheets are commonly used and are available in various forms. Probably the simplest form of fitted sheet or mattress pad is one having the top and sides formed of the same material that is cut and sewn to fit a standard size or range of sizes of mattresses and has an elastic band or cord attached around the lower periphery to draw the lowermost edge of the covering under the mattress to retain the covering in fitted condition. The corners of this type of covering are either entirely straight in the vertical direction or curved inward to facilitate their movement under mattresses of varying heights. Such coverings have the advantage of ease of manufacture and the desirable appearance of the sides being of the same material as the top, e.g. quilted sides and top. They have the disadvantage, however, of utilizing at most only a single elastic band along their lowermost periphery to retain an otherwise inelastic covering on mattresses of varying heights. They have a further disadvantage of being expensive to make if the top panel material, e.g., the quilted material, extends down along the sides of the pad sufficiently to provide enough material to extend at least the full height of mattresses of the greatest thickness (i.e., height), so that the covering can be sold for use with mattresses of varying thicknesses (heights).
Another form of covering is a mattress pad that has a quilted top and an elastic side skirt that further extends downwardly sufficiently to cover the sides and extends under mattresses of varying heights within a standard range for retention of the covering on the mattress. An elastic band or cord typically is attached to the lowermost periphery to facilitate retention of the covering on the mattress. Normally, such coverings are made with corners that are curved in the vertical direction to facilitate fitting under mattresses of varying height. Such pads use skirts formed by joined together elastic and inelastic layers. Other pads use single-layer skirts formed from single panels of inelastic material, which are elasticized by being stitched and gathered with multiple parallel rows of elastic threads sewn into the otherwise inelastic skirt panel, or are elasticized by being stitched or woven with elastic threads. Such mattress coverings have the disadvantage of a different and less desirable appearance of the sides due to the use of the different material rather than being able to use the same material, such as the sheet or quilted material of the top.